1. Field of the Invention
This invention relates to a liquid crystal display and, more particularly to a means for connecting a liquid crystal display using a plastic film and a drive circuit board having a liquid crystal display control circuit for applying a display signal to display elements of the film liquid crystal display.
2. Related Background Art
Liquid crystal displays are well known in which pictures, characters and the like representing information are displayed by driving a liquid crystal device (LCD) by an electrical signal.
An example of a conventional LCD arrangement using glass plates will be described below with reference to FIGS. 9 and 10. An LCD 50 shown in FIGS. 9 and 10 has a pair of glass plates 51 and 55 facing each other. A segment electrode 53 and a portion of a common electrode 54 are provided on an inner surface of one of the pair of the glass plates, i.e., the glass plate 51, and an orientation film 57 is formed as an innermost layer. The other glass plate 55 has another portion of the common electrode 54 and an orientation film 57 formed on its inner surface and is superposed on the glass plate 51. Peripheral portions of these glass plates are sealed with a sealing member 58. A liquid crystal 59 is injected through an inlet 62 (see FIG. 10) to be enclosed between the glass plates. The common electrode 54 is connected to an electrode terminal 52 (see FIG. 10) through a conductive member 60. Polarizing plates 56 and 63 are provided on outer surfaces of the glass plates 51 and 55, respectively, and a reflecting plate 84 is provided on the polarizing plate 83.
To the LCD 50 using the thus-constructed glass plates, a liquid crystal drive circuit board having a liquid crystal display control circuit is connected to enable the LCD 50 to operate for displaying.
Conventionally, a conductive rubber connector, an anisotropic connector, a pin connector or the like, for example, is used as a connection means for this purpose. Japanese Utility Model Publication No. 30930, Showa 59 (1984) discloses a connection means using a conductive rubber connector as shown in FIGS. 11 and 12. That is, conductive rubber connectors 66 each formed of insulating rubber members 66a and 66b and a conductive rubber member 66c interposed between the rubber members 66a and 66b, as shown in FIG. 12, are pinched between a liquid crystal drive circuit board 65 and an LCD 50, and an end of the LCD 50 facing each conductive rubber connector 66 is held by an LCD holding member 67 attached to the drive circuit board 65, as shown in FIG. 11. Electrode terminals of the LCD 50 and connection terminals of the circuit board 65 are thereby connected electrically.
A connection means using an anisotropic connector is also known which is constructed as shown in FIGS. 13 and 14. An anisotropic connector 69 is pinched between a liquid crystal drive circuit board 68 formed of a flexible printed circuit board (FPC) and electrode terminals of an LCD 50 and is bonded to these members by heating and pressing to electrically connect the electrode terminals of the LCD 50 and connection terminals of the circuit board 68.
A connection means using a pin connector is also known which is constructed as shown in FIG. 15. Electrode terminals of an LCD 50 are pinched between a pair of pin connectors 70 so that the electrode terminals and the pin connectors 70 are electrically connected, and the pin connectors 70 are soldered to terminals on a liquid crystal drive circuit board 71.
Thus, each connection means connects the LCD to the liquid crystal drive circuit board. Japanese Utility Model Publication No. 22743, Heisei 3 (1991) discloses another type of connection means with a film liquid crystal cell. This connection means comprises a hot melt type conductive adhesive which is applied to a connector portion and is heated and pressed with a hot pressing jig to form an electrical connection.
The above-described conventional connection means, however, have drawbacks which are described below. That is, the connection means using conductive rubber connector 66 as shown in FIGS. 11 and 12 is unsatisfactory in terms of assembly performance because the connector is liable to topple due to its elasticity, and the connection means using an anisotropic connector 69 as shown in FIGS. 13 and 14 increases the manufacturing cost because it necessitates a special hot pressing machine. Moreover, if a connection failure occurs, it is difficult to repair or reuse the connected portions because of difficulty in disassembling the connected portions. In the case of the connection means using pin connector 70 as shown in FIG. 15, the pitch at which pin connector terminals are arranged is so large that the number of LCD display elements is limited. In the case of the connection means with a film liquid crystal cell, the number of manufacturing steps and the manufacturing cost are increased since a hot melt type conductive adhesive is applied and a hot pressing jig is used. Recently, a film liquid crystal display module called a film LCD, using an engineering plastic film as a transparent base in place of glass, has been developed and put to practical use.
The film LCD is a display device characterized by solving the problem of conventional glass type LCDs, i.e., difficulty in achieving reductions in thickness and weight and improvement in flexibility. Since a transparent plastic film is used as a case, the liquid crystal can be freely formed into a circular shape, an elliptical shape or the like. Also, the film LCD can be easily worked by drilling. Therefore, the film LCD is most suitable for use as a display for cameras and the like.